In critically ill patients, acute renal failure is mostly multifactorial in origin. In general, the simultaneous presence of several deleterious factors tends to aggravate the renal damage. The present case report describes a patient with multifactorial acute renal failure, in whom one of the factors contributing to the renal failure, i.e. transient unilateral post-renal obstruction, apparently protected the obstructed kidney against damage from other causes.